This citation doesn't support your first statement, as the article only covers LMAs. Also, while the difference is significant, the magnitude of the difference is small, you're looking at at 65.6 +/- 5.6 to 73.9 +/- 5.6 cm3.sec-1 (mean +-SEM).
When you consider this is n = 17, the scatter on this data doesn't look so wonderful. You're looking at standard deviations of 22 cm3.sec-1. This data, as I read it, is only significant because they're using non-parametric tests, including Wilcox.
Plus, they emphasise in the discussion that LMA inflation might not actually affect internal jugular caliber / flow, which is probably as important as carotid flow.
This is all surrogate outcome stuff too. No one's looking at ICP, or CBF, or cardiac arrest survival / neuro outcome here.